UI基础整理-4

触摸事件:
开始触摸:touchesbegan

移动触摸:touchesmoved

结束触摸:touchesended

取消触摸:touchescanceled

//开始触摸

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ }

//移动触摸

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ }

//结束触摸

- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ }

//取消触摸

-(void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ }

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//获取触摸设备的对象

UITouch *touch = [touches anyObject];

//获取前一个点

CGPoint p1 = [touch previousLocationInView:self];

//获取当前的点

CGPoint p2 = [touch locationInView:self];

//根据两个点的横纵向距离来计算出移动结果，并将值赋给self.center更新位置

self.center = CGPointMake(p2.x - p1.x + self.center.x, p2.y - p1.y + self.center.y);

//UILabel、UIImageView的用户交互默认是关闭的

responer:

处理过程 : 被触摸视图 –> 传给父视图 –> View –> 视图控制器 –>window –>application …遗失

查询过程 : 硬件设备–> Application –> window –> 视图控制器 –> View –> 视图的各个子视图 最终找到被触摸的视图

防止在滑动屏幕的时候划出去
//屏幕尺寸

#define kWidth [UIScreen mainScreen].bounds.size.width

#define kHeight [UIScreen mainScreen].bounds.size.height

//视图边长的一半

#define kHalfSide self.bounds.size.width/2

//左极限

#define LeftMargin kHalfSide

//右极限

#define RightMargin kWidth - kHalfSide

//上极限

#define TopMargin kHalfSide

//下极限

#define BottomMargin kHeight - kHalfSide

if
(self.center.x<LeftMargin)
{

CGPoint
p =
CGPointMake(LeftMargin+1,self.center.y);

self.center=
p;

}elseif(self.center.x>RightMargin){

CGPoint
p =
CGPointMake(RightMargin-1,self.center.y);

self.center=
p;

}elseif(self.center.y<TopMargin){

CGPoint
p =
CGPointMake(self.center.x,TopMargin+1);

self.center=
p;

}elseif(self.center.y>BottomMargin){

CGPoint
p =
CGPointMake(self.center.x,BottomMargin-1);

self.center=
p;

}else{
//获取触碰设备的对象
UITouch*touch
= [touches
anyObject];
//获取前一个点
CGPointp1
= [touch
previousLocationInView:self];
//获取当前的点
CGPointp2
= [touch
locationInView:self];

//根据两个点的横纵向距离来计算出移动结果,并将值赋给self.center更新位置
self.center=CGPointMake(p2.x-p1.x+self.center.x,
p2.y-p1.y+self.center.y);
}